US5523949A - Method and apparatus for an improved autopilot system providing for late runway change - Google Patents

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Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/04—Control of altitude or depth
  • G05D1/06—Rate of change of altitude or depth
  • G05D1/0607—Rate of change of altitude or depth specially adapted for aircraft
  • G05D1/0653—Rate of change of altitude or depth specially adapted for aircraft during a phase of take-off or landing
  • G05D1/0676—Rate of change of altitude or depth specially adapted for aircraft during a phase of take-off or landing specially adapted for landing

Definitions

• the present invention relates to the aircraft autopilot art and, in particular, to an improved autopilot system which allows the flight crew to maintain autopilot engagement while making a late runway change during approach.
• a problem frequently encountered by commercial aircraft flight crews on approach to an airport is runway re-assignment.
• As the aircraft approaches an airport it is assigned a runway and an approach profile by air traffic control. Due to various conditions that can occur, an aircraft is often re-assigned from one runway to another and is expected to make a smooth transition thereto.
• Such re-assignment may happen after the flight crew has engaged the autopilot and after the aircraft's on board instrument landing system (ILS) has captured either the assigned runway's localizer signal (which defines lateral movement within the approach profile) and/or glideslope (which defines the desired flight path to the assigned runway).
• IVS instrument landing system
• an improvement allows the flight crew to select a new ILS runway without disengaging the autopilot.
• the improvement includes an actuator which is actuated by the flight crew to initiate a desired runway change.
• Provided logic control means responds to the actuation of the actuator to:
• the above described logic control means includes means responsive to actuation of the actuator subsequent to retuning of the ILS to the new runway to rearm the localizer and glideslope for the new approach.
• an improved method for allowing the flight crew to select a new ILS approach without disengaging the autopilot comprises the steps of:
• the provided logic control means further performs the step of responding to actuation of said actuator subsequent to retuning of the ILS to the new runway to rearm the localizer and glideslope for the new approach.
• FIG. 1 illustrates an aircraft on approach to a runway and depicts prior art autopilot systems which do not allow tuning of the ILS to a new approach when the autopilot is engaged;
• FIG. 2A a depicts an autopilot flight director system mode control panel
• FIG. 2B depicts the pilot's control wheel with autopilot disarm switch
• FIG. 3 depicts an aircraft's primary flight display
• FIG. 4 depicts an aircraft on approach to a runway and illustrates, in accordance with the present invention, the zone over which the ILS can be returned to a new approach without autopilot disengagement;
• FIG. 5 is a logic flow diagram illustrating the steps performed by the control logic in accordance with the preferred embodiment of the invention.
• FIG. 6 illustrates mode changes as indicated by the primary flight display during a transition in which localizer, but not glideslope has been captured
• FIG. 7 illustrates mode changes as reflected by the primary flight display in an approach transition wherein glideslope, but not localizer, has been captured
• FIG. 8 illustrates mode changes, as depicted by the primary flight display, during an approach transition wherein both localizer and glideslope have been captured.
• FIG. 1 is a side profile of a commercial aircraft 10 on approach to a runway 12.
• the aircraft 10 in approaching an airport will be assigned clearance for an approach to a given runway by air traffic control.
• the flight crew of the aircraft 10 will commonly engage the autopilot and tune their onboard instrument landing system (ILS) to the guidance signal corresponding to the assigned runway.
• the guidance signal includes a localizer, which defines the lateral position of the aircraft on approach and a glideslope signal, defining the glideslope 14 to the assigned runway 12.
• Both localizer and glideslope signals are individually captured by the autopilot flight director system (AFDS) which is a part of the aircraft's autopilot. Once captured, localizer and glideslope signals are used to guide the aircraft 10 to the runway 12.
• AFDS autopilot flight director system
• FIG. 2A illustrates a conventional commercial aircraft autopilot flight director system (AFDS) mode control panel, indicated generally at 30.
• AFDS autopilot flight director system
• A/P autopilot
• F/D Flight Director
• A/T autothrottle
• A/T autothrottle right arm switch
• climb/continuous thrust switch 44 To the right of the autopilot switch 32 is an autothrottle (A/T) left arm switch 40 and an autothrottle right arm switch 42.
• A/T autothrottle left arm switch 40
• autothrottle right arm switch 42 Directly below the autothrottle arm switches 40, 42 is a climb/continuous thrust switch 44.
• IAS MACH reference switch 46 To the right of the autothrottle arm switches 40, 42 is an inertial airspeed (IAS) MACH reference switch 46 which allows the flight crew to enter a desired aircraft speed either as an airspeed value or a MACH number.
• the selected value is displayed in an IAS/MACH digital display 48 positioned directly below the switch 46.
• IAS/MACH selector switch 50 Below the digital display 48 is an IAS/MACH selector switch 50.
• To the right of the selector switch 50 are three vertical switches with indicator lights; 1) LNAV switch 52 with its corresponding indicator light 54, 2) VNAV switch 56 with its corresponding indicator light 58, and 3) a flight level change (FLCH) switch 60 with its corresponding indicator light 62.
• LNAV switch 52 With its corresponding indicator light 54
• VNAV switch 56 With its corresponding indicator light 58
• FLCH flight level change
• a heading/track hold switch 72 To the right of the autopilot disengage bar 70 is a heading/track hold switch 72 and it's corresponding indicator light 74. Above the heading/track hold switch 72 is a bank limit selector switch 76 which, as shown, allows selection from an "AUTO" position through 5° increments to a maximum bank limit, here indicated as "25".
• a digital display 78 which indicates the heading/track of the aircraft. Whether heading or track is displayed is determined by a heading/track reference switch 80 which is positioned directly above the heading/track display 78.
• a vertical speed/flight path angle reference switch 82 To the right of the heading/track reference switch 80 is a vertical speed/flight path angle reference switch 82. Directly below the vertical speed/flight path angle reference switch 82 is a digital display 84 which, as determined by switch 82, reads out the vertical speed or flight path angle value as input by the flight crew. Directly below the digital display 84 is a vertical speed/flight path angle selector 86.
• the selector 86 is a thumbwheel driven switch which allows the flight crew to input a "down" value by actuating the selector 86 in one direction or "up” value by actuation of selector 86 in the opposite direction, as indicated by an adjacent legend 88.
• the flight crew inputs a desired vertical speed or flight path angle via the vertical speed/flight path angle switch 90 with its corresponding indicator light 92, which is to the right of the selector 86.
• altitude hold switch 94 To the right of the vertical speed/flight path angle switch 90 is an altitude hold switch 94 with its corresponding indicator 96. Above the altitude hold switch 94 is an altitude selector 98.
• the altitude selector is controllable by the flight crew in an "auto"mode or increments of "1000" mode. In the increments of "1000" mode, turning the altitude selector 98 increments or decrements the altitude value displayed in the altitude window 100 by thousands of feet. With the "auto" mode selected, turning the altitude selector increments or decrements the altitude value displayed in the window at a variable rate, depending on the amount of altitude change commanded by the turning of the selector.
• an altitude window 100 which provides a digital display of the selected altitude.
• a localizer switch 102 With its corresponding indicator 104. Directly below the localizer switch 102 is an approach switch 106 with its indicator light 108.
• FIG. 2B Shown in FIG. 2B is a diagram of tile flight crews'control wheel 110 which, in the normal manner, is provided with an autopilot disengage switch 112.
• the automatic flight control system consists of an autopilot flight director system (AFDS) and an autothrottle system.
• AFDS autopilot flight director system
• FMC flight management computer
• the AFDS and autothrottle are controlled automatically by the FMC to perform climb, cruise, descent and initial approach flight path guidance.
• Final approach and landing guidance is provided by the AFDS with control inputs from an ILS system with the pilot controlling speed inputs to the autothrottle through the speed selector 50.
• the AFDS normally is comprised of three autopilot flight director computers and the mode control panel 30.
• the mode control panel 30 provides control of the autopilot, flight director, altitude alert, and autothrottle systems.
• the mode control panel 30 is used to select and activate AFDS modes and establish altitudes, speeds, and climb/descent profiles.
• the AFDS's provide control of the flight directors and autopilots. Flight director information is displayed on the priming/flight display (PFD), an example of which is illustrated in FIG. 3.
• the AFDS does not have direct control of the flight control surfaces.
• the autopilot controls the elevators, ailerons, flaperons, and spoilers through the flight control system. Autopilot rudder commands are added only during an autopilot approach and landing. The autopilot controls nose wheel steering during roll out after an automatic landing.
• the mode control panel 30 mode switches are used to select automatic control modes.
• the light in the lower half of each switch illuminates to indicate that the mode is selected.
• Mode engagement is indicated by the PFD (see FIG. 3) roll and pitch flight mode annunciation.
• flight control modes engage with a single push of a switch. These modes are: flight level change, via flight level change switch 60, heading hold, via heading/track hold switch 72 in conjunction with heading/track reference switch 80, track hold, via heading/track hold switch 72 in conjunction with heading/track reference switch 80, heading select, via heading/track selector 76, track select, via heading/track selector 76, vertical speed, via vertical speed flight path angle switch 90 in conjunction with vertical speed/flight path angle reference switch 82, flight path angle, via vertical speed/flight path angle switch 90 in conjunction with vertical speed/flight path angle reference switch 82, altitude hold, via altitude hold switch 94, climb thrust, via climb/continuous thrust switch 44 and continuous thrust, via climb/continuous thrust switch 44.
• modes arm or engage with a single push. These modes are: lateral navigation, via LNAV switch 52, vertical navigation, via VNAV switch 56, localizer, via localizer switch 102, and approach, via approach switch 106. All modes except localizer and approach can be disengaged by selecting another
• the flight crew can enter desired target values for mode. flight, via mode control panel 30 for: airspeed and MACH, as indicated in display 48, heading and track, via display 78, vertical speed and flight path angle, via display 84, and altitude, via display 100.
• mode control panel 30 for: airspeed and MACH, as indicated in display 48, heading and track, via display 78, vertical speed and flight path angle, via display 84, and altitude, via display 100.
• the autopilot is engaged by pushing either of the two autopilot engage switches 32, 34. Normal autopilot disengagement is through the control wheel 110 autopilot disengage switch 112.
• the airspeed indicator 152 is generally rectangular, indicating in a central window 154 the aircraft's current airspeed, here indicated as "300". From the bottom to the top of the airspeed indicator 52 are corresponding lower to higher airspeed values, here ranging from a value of "240" to a value of "360”. Opposite the indicated airspeed 154 is a selected speed bug 156, here indicating that the aircraft's actual airspeed corresponds to that selected by the flight crew. At the top of the airspeed indicator 152 is an indication of the selected speed, here indicated as MACH 0.82. At the bottom of the airspeed indicator 152 is an indication of the current MACH of the aircraft, here indicated as "820".
• attitude, steering and miscellaneous indication display 160 To the right of the airspeed indicator 152, and centrally located on the PFD 150 is the attitude, steering and miscellaneous indication display 160.
• This display includes a conventional representation of the position of the aircraft wings 162, 164 relative to a pitch up or down scale 166 with a relative roll scale 168. Displayed below display 160 is a semi-circular display of aircraft heading and track 170.
• an indicator 172 here displaying "A/P” indicating that the autopilot flight director systems have been activated.
• a flight mode annunciation display 174 which includes a portion identified as "SPD” to indicate the autothrottle thrust mode, a central display to indicate the aircraft's roll mode, here indicated as “LNAV”, and a right hand portion, indicating the aircraft's pitch mode, here indicated as "VNAV PTH”.
• air traffic control would issue clearance for an approach to a given runway.
• the flight crew would then, typically, engage the autopilot, via the autopilot engage switches 32 and/or 34 and, via the ILS system, tune to the guidance signals corresponding to the assigned runway.
• the ILS system would then proceed to capture either localizer, glideslope or both localizer and glideslope for the assigned approach.
• the improved autopilot (in particular, AFDS) according to the present invention, provides for ILS retuning without disengagement of the autopilot, as depicted generally in FIG. 4.
• FIG. 4 shown is an aircraft 200 approaching a runway 202.
• the flight crew has been assigned to a particular runway 202 and that the crew has engaged the autopilot and that the ILS system has captured either localizer and/or glideslope.
• the present invention allows for retuning of the ILS system without disengagement of the autopilot so long as the aircraft has not descended to a radio altitude of 1500 feet.
• the flight crew does not need to follow the elaborate procedure described above for ILS retuning and, during the transition to the new assigned runway, has reduced workload due to the autopilot remaining engaged.
• the improvement according to the present invention is inhibited and the flight crew must disengage the AFDS to discontinue the approach. This is necessary to allow sufficient time for AFDS internal checks to preserve automatic landing integrity.
• FIG. 5 is a logic flow diagram illustrating the sequential steps performed by the present autopilot improvement to provide the functionality described above.
• the system starts at block 250, indicating that the aircraft is on approach to an assigned runway with the autopilot engaged. If a transition to a new runway assigmnent is desired, the flight crew selects the approach switch 106. The system first checks at a block 260 to determine whether or not the aircraft is at a radio altitude greater than 1500 feet. If it is not, block 270 is entered and, as described herein above, the present improvement is inhibited and the flight crew must manually disengage the autopilot as in prior art designs.
• FIG. 6 illustrates the change in the flight mode annunciation portion 174 of the primary flight display, (shown in FIG. 3). Note that the roll indication transitions from localizer to the flight crew selected mode, here assumed to be heading hold. Also, note that the current pitch mode, here assumed to be VNAV PTH is retained.
• FIG. 7 illustrates the PFD flight mode annunciation display corresponding to this transition.
• the current roll mode, LNAV is retained.
• the pitch mode here assumed to be glideslope capture (G/S) is transitioned to the preselected pitch mode, here assumed to be vertical speed (V/S).
• G/S glideslope capture
• V/S vertical speed
• the sequence at block 330 is entered.
• the roll mode of the aircraft is transitioned to the preselected mode, here assumed to be either heading or track hold.
• the pitch mode of the aircraft is transitioned to the preselected mode, here assumed to be either vertical speed (V/S) or flight path angle (FPA).
• V/S vertical speed
• FPA flight path angle
• the PFD flight mode annunciation display corresponding to block 330 is shown in FIG. 8.
• the roll mode of the aircraft assumed to be localizer capture
• transitions to the preselected aircraft roll mode here assumed to be heading hold.
• the aircraft's pitch here assumed to be glideslope capture (G/S)
• transitions to the preselected pitch mode here assumed to be vertical speed (V/S).
• the sequence at block 340 is entered.
• the aircraft's current pitch mode and current roll mode are retained.
• the ILS localizer and glideslope capture is disarmed. ILS tuning remains enabled to allow tuning to the new assigned runway.
• an improved autopilot flight director system has been described which allows the flight crew to transition from one approach assignment to another without disengagement of the autopilot.

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• Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Automation & Control Theory (AREA)
• Traffic Control Systems (AREA)

Abstract

Description

Claims (21)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23098057

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Cited By (33)

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Citations (20)

• 1994
  • 1994-08-05 US US08/286,317 patent/US5523949A/en not_active Expired - Lifetime
• 1995
  • 1995-08-07 DE DE69512423T patent/DE69512423T2/en not_active Expired - Lifetime
  • 1995-08-07 WO PCT/EP1995/003149 patent/WO1996004597A1/en active IP Right Grant
  • 1995-08-07 AU AU32579/95A patent/AU3257995A/en not_active Abandoned
  • 1995-08-07 EP EP95929093A patent/EP0775336B1/en not_active Expired - Lifetime

Patent Citations (20)

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